Perhaps the most common tool in the machinists's or woodworker's tool kit is the screwdriver, or rather collection of screwdrivers of different sizes that an artisan must have available to drive and remove the slotted-head screws and bolts of different sizes that he regularly encounters. This range does not include screws of the sizes used by watchmakers, at one end of the scale, and the cap screws which are driven or removed with wrenches, at the other end of the scale, but for the screws of sizes between those extremes a mechanic usually carries half-a-dozen or so screwdrivers of different dimensions. This multiplication has been necessary prior to my invention to be described hereinafter because of the different widths of slots in screws of various sizes and the different torques required to tighten or loosen screws of different diameters. It has been necessary to use small screwdrivers with thin blades to engage small screws with narrow slots and large screwdrivers with thicker and wider blades to rotate large screws with wider slots.